Influence of powder morphology on properties of ceramic injection moulding feedstocks

The powder–binder-mixture is the most critical aspect in the injection moulding processing chain, because the feedstock properties determine the success of the following steps, i.e. excellent flowability in the injecting phase and high green strength during debinding. Therefore, nearly spherical particles which pass each other easily in the feedstock stream are advantageous. The applicable particle size is limited in order to reach high solids loadings which are connected with the specific powder surface. According to this, in this study a very unfavourable powder was introduced into a feedstock. The investigated β-alumina powder consists of plate-like primary particles and has a specific surface of 25 m2/g. During mould filling the particles orient in the feedstock stream which affects the debinding and sintering behaviour and is the source of defects. The influence of the plate-like shape on defect formation is demonstrated in comparison to spherical-shaped particles having the same specific surfaces.